This application claims the benefit of the Korean Application No. P2002-40994 filed on Jul. 13, 2002, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a tungsten heavy alloy applied to a penetrator material of a penetrating splinter shell, and more particularly, to a tungsten material for a penetrating splinter shell and forming method thereof enabling a penetrator to perforate a hard target on high-speed impact as well as having the following splinter cause a severe damage and incendiary effect on an inner component by changing a breakage characteristic of the material into brittle fracture from ductile fracture in a manner that a mechanical characteristic of the material is adjusted by controlling a sintering condition and a composition ratio of a tungsten heavy alloy material having Mo added thereto.
2. Discussion of the Related Art
FIG. 1 illustrates a picture of a typical microstructure(compositional mode of SEM) of 90W-7Ni-3Fe tungsten heavy alloy according to a related art.
Referring to FIG. 1, circular grains are tungsten of body-centered cubic(BCC) unit cells and a portion, which surrounds the circular grains and in which solid solution of the tungsten is contained in part, is a matrix of Nixe2x80x94Coxe2x80x94Fexe2x80x94W alloy of face-centered cubic(FCC) unit cells.
The material is a kind of composite constructed with a tungsten particle having a hard property and the matrix having a soft property.
Meanwhile, the material is prepared by liquid phase sintering. The prepared pellet is maintained at 1,000xcx9c1,300xc2x0 C. for a predetermined time(2xcx9c10 hours), a series of water quenching is carried out on the pellet repeatedly, a cold rolling process is carried thereon, and the pellet is then aged.
The pellet prepared by the above method is widely used as a penetrator material of a kinetic energy projectile as well as is applied to other civilian industry fields of weight balance, radiation shield, processing tool, and the like.
Depleted uranium(hereinafter abbreviated DU) is currently used as a material of an armored plate breaking penetrator as well as the tungsten heavy alloy material.
It is known that material physical properties of DU is superior to those of tungsten heavy alloy as well as that penetration performance of DU is superior to that of tungsten heavy alloy approximately 10%. The reason why the penetrating performance of DU is superior to that of tungsten heavy alloy is that a behavior of high-speed transformation of DU is different from that of tungsten heavy alloy. A difference between the high-speed transformation behaviors of the two materials is shown in FIG. 2A and FIG. 2B.
Namely, tungsten heavy alloy, as shown in FIG. 2B, has severe transformation on penetration so that a cusp of the penetrator is changed into a mushroom shape to increase a diameter of the penetrator. Hence, a penetration resistance increases to reduce the penetrating performance. On the other hand, DU, as shown in FIG. 2A, develops so-called self-sharpening that causes a local fracture easily due to adiabatic shear bend at an edge of the cusp of the penetrator. Hence, a diameter of the penetrator of DU becomes smaller than that of tungsten heavy alloy so that a penetration resistance of DU is lowered than that of tungsten heavy alloy. Therefore, the penetrating performance of DU is relatively increased.
There are several disadvantages to using DU, such as hydrogen brittleness, corrosion, environmental pollution, related medical illness, and the like. Therefore, notwithstanding that DU is superior to tungsten heavy alloy in penetrating power, the latter is on the balance more suitably useable.
Specifically, environmental pollution and badness for human healthcare are fatal so that there are many limitations on use of DU.
Military arms are variously developed lately to make use of the tungsten heavy alloy material for the kinetic energy projectile as attacking arms systems for missile defense, anti-ship, and anti-craft in Navy. Specifically, a penetrating splinter shell having multi-functions of splinter diffusion penetration and incendiary effect is badly demanded.
Meanwhile, unlike the penetrating mechanism of target penetration by self-sharpening of the penetrator itself, a Wxe2x80x94Cu material is known well for the target penetration by splinter diffusion. Yet, when considering the relative correlation of tensile strength and compression yield strength of the Wxe2x80x94Cu material, is to apparent that the tensile strength is, relatively, too high. Hence, the Wxe2x80x94Cu material fails to be superior to that of the present invention in the splinter-diffusion penetrating performance.
Accordingly, the present invention is directed to a diffusing-splinter penetration type tungsten heavy alloy penetrator material that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a diffusing-splinter penetration type tungsten heavy alloy penetrator material enabling penetration of a target not by self-sharpening of a penetrator itself but by diffusing splinters.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a diffusing-splinter penetration type tungsten heavy alloy penetrator material according to the present invention includes 90xcx9c95 wt % W powder, 3.0xcx9c8.0 wt % Mo powder, 0.5xcx9c3.0 wt % Ni powder, and 1.0xcx9c4.0 wt % Fe powder.
In another aspect of the present invention, a method of forming a diffusing-splinter penetration type tungsten heavy alloy penetrator material includes the steps of mixing 90-95 wt % W powder, 3.0-8.0 wt % Mo powder, 0.5-3.0 wt % Ni powder, and 1.0-4.0 wt % Fe powder with each other, compacting the mixed powders to form a green blank, and sintering the compacted green blank.
Preferably, the compacting step is carried out by Cold Isostatic Pressing.
Preferably, the sintering step is carried out for 2xcx9c5 hours at 1,350xcx9c1,450xc2x0 C.
Preferably, the sintering is carried out at an ambience of none-oxidation or a reducing ambience of hydrogen gas.
The present invention is characterized in that a mechanical characteristic is controlled by an intermetallic compound produced by adjusting an alloy ratio by adding Mo to a tungsten heavy alloy composition and by controlling a sintering condition.
Therefore, the present invention enables to provide a heavy alloy material for a splinter shell suitable for penetrating the target on high-speed impact and causing a severe damage and incendiary effect on an inner component by changing a breakage characteristic of the material into brittle fracture from ductile fracture.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.